The present disclosure generally relates to luminescent solar collectors. In particular, it relates to methods of increasing the concentration of light at the edge of such a solar collector to produce greater electrical power.
Luminescent solar collectors (LSCs), or luminescent solar concentrators, are beneficial for capturing solar energy for use. An LSC usually comprises a sheet, generally a molded polymer, having a surface area. Dispersed, dissolved, or doped within the sheet is a fluorescent material. When the sheet is exposed to light (radiation energy), the material absorbs a portion of the light and emits the absorbed light energy at different, longer wavelengths. This light is then transported, via total internal reflection, to at least one edge of the sheet. The concentration of light from a large surface area to a smaller surface area (the edge) is also known as the “edge glow” effect. Due to this effect, the amount of light (i.e. energy) available at the edge is related to the total surface area of the sheet. A light energy converter, such as a silicon photocell, can be attached to at least one edge of the LSC to convert the light energy transmitted thereto into electricity. This enables the LSC to concentrate the maximum amount of light at its edge or edges to generate more electrical power.
The amount of light (i.e. energy) available at the edge is related to the total amount of incident light contacting the sheet; the type of polymer matrix; and the absorption and emission efficiencies (i.e. quantum yield) of the fluorescent dye. In summary, the edge emission is related to the total amount of light contacting the sheet which is absorbed by a dye and eventually directed to the edge. A dye having a high quantum yield is desirable because light lost during fluorescence is also lost to the light energy converter. It is also desirable to collect as much of the light energy on the sheet as possible to produce more unit power per area on the LSC. In addition, not capturing wavelengths in the visible spectrum produces possibly undesired color in the LSC and potentially allows the LSC sheet to be somewhat visibly transparent. Capturing this energy would reduce any color in the LSC sheet and make the LSC sheet more opaque, resulting in the better shielding of structural and accessory features, such as connection materials, wiring, etc., from view.